Biomass Conversion and Biorefinery
·
2024
·
IF 3.5
Zhang Wenrui,Huang Jintian
The non-biodegradability and microtoxicity of harmful anions in water, especially hexavalent chromium, have caused serious damage to the environment and human health. Therefore, research on efficient and environmentally friendly adsorbents for the removal of Cr(VI) becomes essential. In this paper, we propose for the first time to effectively remove Cr(VI) anion by aminated graphene oxide/cellulose oxide nanocellulose/sodium alginate porous materials (NH 2 -GO/NOC/SA) prepared by cross-linking aminated graphene oxide with biomass materials (oxidized nanocellulose and sodium alginate) via epichlorohydrin. The porous materials were characterized using tools such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), electroluminescence (EDS), Brunauer Emmett Teller (BET), and X-ray photoelectron spectroscopy (XPS) analysis. The optimum adsorption performance of the porous material was obtained by varying the initial concentration (from 100 to 500 mg/L), pH (from 1 to 8), and adsorption time (from 15 min to 72 h) of the Cr(VI) solution. The analysis of the adsorption data showed that the adsorption process was more in line with the pseudo-second-order kinetic equation and Langmuir isotherm model, and the equilibrium adsorption amount reached 394.1 mg/g. The adsorption of Cr(VI) on the NH 2 -GO/NOC/SA porous material was achieved by electrostatic interactions, Schiff base chemical bonding energy, ion exchange, protonation, precipitation, and hydrogen bonding. In conclusion, the experimental results show that the biomass adsorbent NH2-GO/NOC/SA can be consistently applied to remove Cr(VI) from wastewater. Graphical
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ENVIRONMENTAL RESEARCH
·
2026
·
IF 8.2
Haidong Li,Yuankun Yang,Han Song,Yi Yang,Hui Gong,Xinwen Chen,Weiguo Tu,Xuemei Luo,Yu Liu,Shu Chen
Potassium butyl xanthate (PBX) is a widely used flotation collector that can persist in tailings waters and may generate toxic by-products. In sunlit tailings ponds, sulfite (S(IV)), Cr(VI), and PBX may coexist under certain conditions, yet the impact of coupled S(IV)-Cr(VI) photochemistry on PBX attenuation remains unresolved. We quantified PBX degradation in a sunlight/S(IV)/Cr(VI) system across pH 3-10, covering tailings-water variability and pH-driven speciation. The process enabled simultaneous PBX removal and Cr(VI) detoxification, with optimum performance at mildly acidic-neutral pH. At pH 6, k obs increased from 3.9×10 -3 min -1 (sunlight) to 2.35×10 -2 min -1 (sunlight/S(IV)) and 3.38×10 -2 min -1 (sunlight/S(IV)/Cr(VI)), confirming synergy. Quenching/probe tests and time-resolved EPR implicated SO 4 •− , •OH, and Cr(V), indicating pH-dependent coupling between the sulfite radical chain and the Cr(VI)/Cr(V)/Cr(III) cycle. DFT and LC-MS showed acidic hydrolysis/self-decomposition of PBX to CS 2 at pH 3, whereas near-neutral conditions favored radical/Cr(V)-mediated oxidation with efficient Cr(VI) reduction. Outdoor natural-sunlight tests using laboratory-generated flotation wastewater prepared from raw ore collected from the mine (with spiked S(IV) and Cr(VI)) achieved 90% PBX removal within 60 min at pH = 6, T ≈ 35-36 °C and solar irradiance ≈ 750-850 W m -2 ,indicating preliminary feasibility of the coupled process in a scenario-based flotation-wastewater matrix.
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SCIENCE OF THE TOTAL ENVIRONMENT
·
2020
·
IF 6.551
Lixun Zhang,Fangxin He,Wei Mao,Yuntao Guan
It is still a great challenge to find an eco-friendly, easy-to-synthesize, and cheap adsorbent to rapidly remove Cr(VI) to ppb level in the Cr(VI)-polluted water. Herein, a new layered double hydroxide nanocage intercalated with diethyldithiocarbamate (DDTC-LDH) was fabricated via a facile calcination-rehydration method. The DDTC-LDH rapidly decreased Cr(VI) concentration from 5 to <0.05 mg/L within 35 min, and only a few seconds were required to completely remove it at an initial concentration of 0.5–1 mg/L, primarily attributed to the effective adsorption-reduction of Cr(VI) to Cr(III) by sulfur atoms in C S and C S groups. Attractively, the generated Cr(III) was also quickly removed to below 0.1 mg/L via an opportune Lewis hard-hard interaction with C–SO x groups produced through C S oxidation. Additionally, Cr(VI) could be removed by DDTC-LDH at a wide pH application range (3.17–10.78) and with weak effects by coexisting anions (Cl − , NO 3 − , CO 3 2− , SO 4 2− , and PO 4 3− ). We systematically analyzed and proposed the mechanisms for Cr(VI) removal by the DDTC-LDH, orderly containing electrostatic attraction, Cr(VI) complexation by sulfur atoms in C S and C S groups, reduction of the Cr(VI) to Cr(III) by the C S and C S groups, and Cr(III) complexation by sulfur atoms in C–SOx groups. Our results provide new insights into the Cr(VI) removal using organosulfur compounds , that is to say, the organosulfur group Lewis hardness increased (from C–S to C–SOx) as the Cr species Lewis hardness increased (from Cr(VI) to Cr(III)), so as to opportunely ensure fast and efficient capture of both Cr(VI) and Cr(III) via Lewis acid-base interactions.
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CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Peng Li,Yifei Li,Mengyao Qi,Xia Zhang
In recent years, most of the researches on nanozymes have focused on improving their catalytic activity and direct synthesis, but this task is still very complicated. Bimetallic oxides are particularly popular because of their mixed valence and special structure. In this study, iron-manganese bimetallic oxide nano-cubes (IMBO NCs) were prepared by a rapid and effective solvothermal synthesis technique, and showed excellent oxidase-like activity. The exposure of Cr(III) and Cr(VI) inhibited and enhanced the catalytic activity of IMBO NCs respectively. On this basis, a simple, economical and accurate colorimetric sensor was established by combining with 3,3′,5,5′-tetramethylbenzidine (TMB). Using oxidase activity instead of traditional peroxidase activity to detect Cr(III) and Cr(VI) greatly shortens the detection time. The method has also been successfully applied to the quantitative monitoring of Cr(III) and Cr(VI) in lake water. This study provides theoretical support for the effective design of bimetallic oxide nanozyme activity and can guide the development of accurate detection systems for the analysis of Cr(III) in food and Cr(VI) in environment.
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ENVIRONMENTAL TECHNOLOGY
·
2024
·
IF 2.2
Hao Zhang,Jiahong Wang,Peiling Han,Zhi Hu
Industrial wastewater often contains potentially toxic metals and it’s chelates, posing serious threats to human health and aquatic ecosystems, and adsorption is frequently used for the minimization of potentially toxic metals from water. In this study, citric acid modified MOF-808 (MOF-808-CA) was prepared by using citric acid to modify MOF-808 for the removal of Cr(III) and Cr(III)-EDTA from wastewater. MOF-808-CA with the BET surface area of 653.59 m2 g−1 and the pore volumes of 0.467 cm3 g−1 was successfully synthesized. The adsorption of Cr(III) and Cr(III)-EDTA by MOF-808-CA was 40.46 and 17.03 mg g−1 at pH 4.0 and 25°C, respectively. The adsorption isotherms and adsorption kinetics of Cr(III) and Cr(III)-EDTA were summarized using Langmuir-Freundlich isothermal adsorption model and the pseudo-second-order model. Even in high salinity wastewater (35,000 mg L−1), MOF-808-CA displayed a strong affinity for Cr(III) and Cr(III)-EDTA. The site energy (E*) values reduced with the increasing of adsorption capacities, and Cr(III) and Cr(III)-EDTA firstly dominated the high-energy adsorption sites before low-energy adsorption sites. The average site energies for the adsorption of Cr(III) and Cr(III)-EDTA by MOF-808-CA were 26.7 and 24 kJ mol−1, respectively, and the differences in the average site energies further illustrated the essential differences in their adsorption mechanisms. The adsorption by electrostatic adsorption and surface complexation were the main adsorption mechanisms for Cr(III) on MOF-808-CA, whereas hydrogen bonding and complexation were the main adsorption mechanisms for Cr(III)-EDTA on MOF-808-CA. The results showed that the MOF-808-CA adsorbent has a great potential for the removal of both Cr(III) and Cr(III)-EDTA from aqueous solutions.
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JOURNAL OF HAZARDOUS MATERIALS
·
2024
·
IF 12.2
Qian Guo,Dongmei Yu,Jing Yang,Ting Zhao,Dan Yu,Lei Li,Duanjie Wang
The distribution characteristics of Cr(VI) species in contaminated soil is crucial for soil remediation; however, there is currently a lack of methods for analysing anionic Cr(VI) species in soil. This study has developed a novel sequential extraction method for speciation of Cr(VI) and Cr(III). Besides extraction experiments, simulated chromium species were prepared to verify the presence of proposed chromium species. The results show that Cr(VI) species in soil can be categorized into water-soluble Cr(VI), electrostatically adsorbed Cr(VI), Cr(VI) specifically adsorbed by minerals containing exchangeable Ca 2+ , Cr(VI) specifically adsorbed by hydrous metal oxides, calcium chromate Cr(VI) and stable complexed adsorption Cr(VI). These Cr(VI) species can be selectively extracted by specific solutions through ion exchange or weak acid dissolution. The most stable Cr(VI) species is Cr(VI) complexed by hydrous iron oxides through bidentate ligand binding; only by dissolution of hydrous iron oxides can this Cr(VI) species be leached. The distribution of Cr(VI) species is closely linked to particular soil compositions including exchangeable Ca 2+ and hydrous iron oxides which determinate the Cr(VI) adsorption in soil. Cr(III) species comprise Fe-Cr coprecipitate hydroxides Cr(III), Fe-Mn oxide-bound Cr(III), organic matter-bound Cr(III) and residual Cr(III). Their distribution depends on the types of reductants present in the soil.
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ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2019
·Vol. 26
·期 27
·28361-28371
·
IF 2.914
Yi Yunqiang,Wei Yufen,Tsang Pokeung Eric,Fang Zhanqiang
Aging effects play a crucial role in determining applications of green-synthesised iron-based nanoparticles in wastewater treatment from laboratory scale to practical applications. In this study, iron-based nanoparticles (Ec-Fe-NPs) were synthesised using the extract of Eichhornia crassipes and ferric chloride. Scanning electron microscopy (SEM) revealed that the fresh Ec-Fe-NPs were spherical and had a narrow particle size range (50 to 80 nm). X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) demonstrated that the Ec-Fe-NPs were mainly amorphous in nature and consisted of Fe 0 , FeO, Fe 2 O 3 and Fe 3 O 4 . As they aged, the particle size of the liquid Ec-Fe-NPs gradually increased and then tended to stabilise. Ec-Fe-NPs that were aged for 28 days were only 19% less efficient than fresh material at removing Cr(VI). Extracts aged up to 28 days were also tested, and their antioxidant capacity was found to be 15.4% lower than that of the fresh extracts. Furthermore, the removal efficiency of Cr(VI) using iron-based nanoparticles synthesised with the aged extracts was 67.2%. Finally, the active components of the extracts, which were responsible for the reactivity and stability of the iron-based nanoparticles, were identified by liquid chromatography–mass spectrometry. Overall, green-synthesised iron-based nanoparticles show promise for Cr(VI) removal from wastewater in practical applications.
研究领域:
环境科学
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材料科学
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植物学
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ACS Applied Energy Materials
·
2024
·
IF 5.4
Hao Shi,Haozhen Li,Xing Zhou,Chongqing Yang,Hengyong Tu,Jun Tong,Longkai Xiang,Chao Ma,Lei Zhu,Zhen Huang
Spinels have been widely employed as contact layers (CLs) on metallic interconnects for solid oxide cells (SOCs) with the required electrical conductivity and Cr block ability. In this work, MnCo2O4 spinels doped with different transition metals (Cu, Ni, and Zn) were deposited on precoated SUS441 stainless steel as CLs. A positive doping effect of Cu and Ni on increasing the concentration of Mn4+/Mn3+ and Co3+/Co2+ hopping pairs was observed, whereas a negative doping effect of Zn on electrical conductivity was confirmed, which was reflected in the data of X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectra (XAS). The Cu-doped Mn1Co1.7Cu0.3O4 spinel exhibited the best electrical conductivity with a low area specific resistance (ASR) value of 4.5 mΩ·cm2 at 850 °C. A relative degradation test demonstrated that Mn1Co1.7Cu0.3O4 maintained significant performance during a 200 h isothermal process. Cross-sectional observations revealed that the thickness of the Cr oxide scale formed during the degradation test was much reduced by the Mn1Co1.7Cu0.3O4 CL, which was attributed to the improved resistance to Cr oxidation. The present work shed light on the design of highly conductive CLs in SOCs.
研究领域:
材料科学
·
能源科学
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JOURNAL OF HAZARDOUS MATERIALS
·
2026
·
IF 10.6
Xinlei Zhang,Shiying Yang
The removal of hazardous Cr(III) complexes via advanced oxidation processes can generate highly toxic Cr(VI), posing significant environmental risks. Therefore, there is an urgent need to develop alternative methods that completely suppress the generation of Cr(VI). In this study, with no detectable Cr(VI) in the solution (below the detection limit of 0.004 mg/L), the carbon nanotubes-modified micron-sized zero-valent aluminum (CNTs@mAl 0 ) can effectively remove 99.50% of Cr(III)-EDTA and 83.34% of TOC under the typical acidic conditions of industrial chromium wastewater (pH = 3.00) by activating molecular oxygen. Then the following alkaline precipitation can easily remove the decomplexed free chromium, lowering total chromium concentration to 0.11 mg/L, which meets most national and regional standards, whereas direct alkali precipitation fails to meet them. Serving as a strong electron reservoir (E 0 = - 1.662 V), micron-sized zero-valent aluminum (mAl 0 ) synergizes with highly conductive carbon nanotubes (CNTs) to effectively activate O 2 , facilitating the production of reactive oxygen species (primarily 1 O 2 and •OH) that drive the oxidative decomplexation of Cr(III)-EDTA. Furthermore, the organic ligands are efficiently mineralized, thus preventing Cr(III)’s re-complexation. More interestingly, once the Cr(VI) is possibly generated, it would be rapidly absorbed by CNTs and be immediately reduced by mAl 0 with strong reducing power, thereby completely suppressing the generation of any Cr(VI) in bulk solution. In conclusion, this study presents an environmentally friendly and straightforward treatment system for Cr(III)-complexes, offering an effective solution to mitigate the environmental risks posed by chromium, particularly Cr(VI), in wastewater.
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JOURNAL OF HAZARDOUS MATERIALS
·
2022
·
IF 14.224
Linheng Chen,Weixi Liu,Yang Wu,Jumei Li,Yibing Ma
There is uncertainty in quantifying the toxic effects of total chromium (Cr) in the environment by modeling the toxicity of individual Cr(III) or Cr(VI). In the present study, the effects of Cr(III) and Cr(VI) on barley root elongation were investigated in a hydroponic system where Cr(III) and Cr(VI) combination dose-response experiments under monotoxicity concentration, single-dose addition, and fixed concentration ratios were designed to identify and quantify their combined phytotoxicity of one element with various valences. The results show that the calculated mixed toxicity unit values for 50% inhibition (TU mix50 ) ranged from 1.06 to 1.45, indicating the weak antagonism effects of Cr(III) and Cr(VI) on barley root toxicity. Also, the single-dose group experiment has proved that the EC 50 of Cr(VI) was increased from 71.2 μM to 119.9 μM with Cr(III) addition, which suggested that Cr(III) has antagonism on the toxicity of Cr(VI). While EC 50 of Cr(III) was not affected by Cr(VI) addition. After introducing the expansion coefficient of Cr(III) on Cr(VI) toxicity, both the extended concentration addition model (e-CA) based on the log-logistic and Weibull equations and the extended independent action model (e-IA) could more accurately predict the barley root elongation under Cr(III) and Cr(VI) interaction. The e-CA model based on the Weibull equation had almost the best correlation coefficient (R 2 ) and lowest root mean square error (RMSE) between the measured and predicted values. Finally, the combined toxicity and antagonism of the same element with co-existing different valences simultaneously were successfully and firstly identified and quantified in the present study.
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WATER RESEARCH
·
2018
·
IF 7.051
Guojun Chen,Juncheng Han,Yang Mu,Huimin Yu,Liping Qin
Chromium isotope fractionation analysis is a promising approach for the assessment of microbial Cr(VI) reduction in groundwater. Understanding the mechanisms and other parameters that control Cr isotope fractionation factors (between the product Cr(III) and reactant Cr (VI)) in microbial Cr(VI) reduction is critical to this application. To date, such studies are very limited. Here, the influence of critical factors on observed Cr isotope fractionation during Cr(VI) reduction by Shewanella oneidensis MR-1 under various conditions was investigated. The Cr(VI) concentration and Cr isotope ratio measurements were conducted on unreacted Cr(VI) remaining in solution to determine Cr isotope fractionation factors. The changes in ambient environmental conditions (e.g., pH, temperature) have limited influence on Cr isotope fractionation factors. However, as a result of Cr(VI) consumption as the experiments proceed, the change in bioavailability of Cr(VI) has a significant impact on Cr isotope fractionation factors. For example, in temperature-controlled experiments, Cr isotope fractionation showed two-stage behavior: during Stage I, the values of ε were −2.81 ± 0.19‰ and −2.60 ± 0.14‰ at 18 °C and 34 °C, respectively; during Stage II, as Cr(VI) reduction progressed, Cr isotope fractionation was significantly masked, and the ε values decreased to −0.98 ± 0.49‰ and −1.01 ± 0.11‰ at 18 °C and 34 °C, respectively. Similar two-stage isotope fractionation behaviors were observed in pH-controlled experiments (pH = 6.0 and 7.2) and in experiments with and without the addition of a competing electron acceptor (nitrate). Masking of isotope fractionation in Stage II indicated restrictions on the bioavailability of Cr(VI) and mass-transfer limitations. This study provides an explanation for the variation in Cr isotope fractionation factors during microbial Cr(VI) reduction in the environment, furthering the viability of Cr isotope ratio analysis as an approach in understanding Cr biogeochemical cycling.
研究领域:
环境微生物学
·
同位素地球化学
·
生物修复
·
地球化学
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Desalination and Water Treatment
·
2026
·
IF 3.4
Xiaolan Shen,Zhenbo Peng,Jiang Shen,Wenting Si,Ningru Sun,Hao Li,Rui Shen
In this study, a membrane-free electrodeionization (MFEDI) technology was demonstrated first time for the removal of hexavalent chromium (Cr(VI))-containing wastewater. Two packing configurations, namely, layered semimixed packing MFEDI (LSMP-MFEDI), and fully mixed packing MFEDI (FMP-MFEDI), were comprehensively investigated for Cr(VI)-containing wastewater treatment. During the treatment stage, the treatment capacity of FMP-MFEDI (132 h) was twice that of LSMP-MFEDI (60 h), with the effluent conductivity under 1 μS/cm. The enhancement is primarily due to the initial adsorption of dichromate(Cr 2 O 7 2- ) by quaternary amine groups, which promotes the co-adsorption activity of tertiary amines. More importantly, during the electroregeneration stage, FMP-MFEDI (229.7 mg/L) exhibited higher regenerated average Cr(VI) concentrations than LSMP-MFEDI (170.5 mg/L), along with a reduced energy consumption (0.19 kWh/g for FMP-MFEDI, 0.25 kWh/g for LSMP-MFEDI) and an increased water recovery rates (95.6% for FMP-MFEDI, 94.1% for LSMP-MFEDI). Such an enhanced electroregeneration performance in FMP-MFEDI was because that the strong-base and weak-base anion-exchange resins fully interact to form a “contact face”, which comprises both tertiary and quaternary amine functional groups. The tertiary groups promoted the release of Cr 2 O 7 2- from the quaternary groups, thereby showing a synergistic effect in electro-releasing the adsorbed Cr 2 O 7 2- . This provides abundant localized ion-depletion regions, consequently enhancing the electroregeneration property.
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